Quantification of the cracking in contact subjected to complex loading in fretting wear and fretting fatigue

Abstract The objective of this research focuses on the quantification of the fretting fatigue endurance of XC38 (EA1N) steel alloy used in the TGV axles components. This study mainly concerns the prediction of the crack nucleation and crack arrest conditions under complex fretting and fretting fatigue loadings. Combining experiments and modeling aspect it includes the following two parts. In the first part, fretting wear and fretting fatigue tests have been undertaken and modelized. It was demonstrated a threshold loading condition associated to the crack nucleation process. A specific formulation has been proposed to capture the size effect and provide pertinent and reliable crack nucleation predictions. From this analysis a fretting fatigue crack nucleation boundary has been defined and formalized. The second contribution of this work concerns the formalization of the crack propagation behavior under fretting and fretting fatigue conditions. Specific experiments have been developed to quantify the crack arrest boundaries. By combining crack nucleation, short crack propagation and long crack formulations, the endurance under complex fretting fatigue global situation has been derived. Hence, the fretting fatigue endurance curves have been quantified taking into accounts the respective contribution of fretting and fatigue loadings. Finally a global fretting fatigue chart has been introduced to rationalize the different cracking damages activated under complex fretting fatigue situations.